1. Field of the Invention
The present invention relates to a fibrous material layer intended to be incorporated in an absorbent article such as a diaper, a pant diaper, an incontinence guard, a sanitary napkin and the like, of the type comprising a liquid-pervious topsheet, a liquid-impermeable backsheet, and an absorbent body applied therebetween.
2. Background of the Invention
Absorbent articles of the above-mentioned type are intended for absorption of body fluids such as urine and blood. As a liquid-pervious topsheet, they usually use a nonwoven material, e.g., of spunbond type, which during use is facing the user. It is also previously known to arrange an acquisition layer, between the topsheet and the absorbent body, having the ability to rapidly receive large liquid quantities and to distribute the liquid and store it temporarily before it is absorbed into the underlying absorbent body. This is of great importance, particularly in the thin, compressed absorbent bodies of today which often have a high content of so-called superabsorbents, which certainly have a high absorption capacity but in many cases an absorption rate which is too low to be able to instantaneously absorb the large quantity of liquid which may be emitted within a few seconds when urinating.
A porous, relatively thick acquisition layer, e.g. in the form of a fiber wadding, a carded fiber web, or another type of fiber material, has a high instantaneous liquid acquisition and can store the liquid temporarily until it has been absorbed by the absorbent body. Porous foam materials behave in the same way. Subsequently, the liquid successively is drained into the underlying absorbent core, after which the acquisition layer once again has the capacity to receive liquid from another wetting.
Examples of absorbent articles comprising such porous acquisition layers are disclosed in e.g. U.S. Pat. No. 3,371,667, EP-A-0,312,118 and EP-A-0,474,777.
The present materials which are used as acquisition layers in absorbent articles function well most of the time, but are relatively expensive and may sometimes exhibit an insufficient acquisition rate, particularly in the second and third wetting when large liquid quantities are concerned.
Another problem is that conventional liquid-pervious topsheet materials utilized for absorbent articles of this type, usually a nonwoven material of synthetic fibers, e.g., a spunbond material, often exhibit a liquid acquisition rate which is inferior to the one of the acquisition layer, wherein liquid is able to leak out from the article before it reaches the acquisition layer. Naturally, this problem can be solved by means of utilizing a topsheet material which is very open and thereby exhibits a high liquid acquisition rate. Such an open topsheet material, however, can cause problems with a strength which is too low, and with sharp fiber ends from the acquisition layer which penetrate the open topsheet material and irritate the user.
A material layer of the type mentioned in the introduction is known from WO 99/27876, i.e., a layer of continuous fibers, so-called tow, which have been bonded together in dots, lines or spots of a bonding pattern but which otherwise are substantially unbonded to each other. The material layer exhibits a high liquid acquisition rate also in repeated wettings, high strength and wear resistance, and high comfort. However, there is still room for further development of such a material, particularly when the liquid acquisition properties and the surface dryness are concerned.